Brief interventions to improve treatment outcomes in young cannabis users

Summary of the evidence

  • Unknown effectiveness

Brief interventions for non-treatment seeking young adults (17-25 ys) were found in a systematic review with meta-analysis (Halladay et al., 2019) to have some promising but not conclusive effects when compared to no intervention or usual care in:

  • improving short-term abstinence - 3 months follow-up (OR 1.73, 95 % CI 1.13 to 2.66, 3 studies, N=666)
  • reducing the risk of cannabis use disorders (as measured by the CUPIT tool, a brief self-report screening instrument for detection of currently and potentially problematic cannabis use) (SMD -0.14, 95 % CI -0.26 to -0.01, 7 studies, N=1173)

The results were confirmed in a new systematic review with meta-analysis (Steele et al., 2020) that synthetised the evidence regarding the effects of brief behavioural interventions for adolescents (12–20 years) with problematic substance use. Brief interventions were categorized into motivational interviewing (MI), psychoeducation, and treatment as usual.  The analysis found that:

  • use of MI did not reduce cannabis use days, with a net mean difference of 20.05 days per month (95% CrI: 20.26 to 0.14; moderate SoE)
  • while it confirmed the effectiveness of brief interventions, especially MI, in reducing heavy alcohol use and alcohol use days

Another narrative systematic review (Chazal et al., 2022, 8 studies, N= 2 199) assessed the effectiveness of brief interventions realized in primary care in reducing cannabis use for adolescents and emerging adults. Brief interventions were all based on motivational interviewing techniques or personalized feedback. The results found:

  • no significant reduction of cannabis use after brief intervention was found for most studies, especially in the long term. 


Note: this evidence summary is only valid for the outcomes, target groups, settings and substances/patterns of use described below.